I have found info about disabling if the drop shadow is always on, but not when hovering your cursor. I suspect this is something that can't be changed easily as it is meant to show which icon you are selecting, which I would think is a desireable feature, especially if you have lots of icons on your desktop. This link has some suggestions, but not for doing what you are looking to do.

Do you have Single click to open an item turned on in Folder options? If so that would highlight the item (icon) just by hovering. If its set to double-click and still highlights without clicking...back to the drawing board .

Do you have Single click to open an item turned on in Folder options? If so that would highlight the item (icon) just by hovering. If its set to double-click and still highlights without clicking...back to the drawing board .

Mine is set to single click, but I like having the icon I have selected to highlight when I hover over it.

Do you have Single click to open an item turned on in Folder options? If so that would highlight the item (icon) just by hovering. If its set to double-click and still highlights without clicking...back to the drawing board .